* iOS is very restrictive in it's user interface. It has run well without any lag, but I cannot customize anything other than the wallpaper.
* iPhone is very small. I have low vision, and the bigger 5.5-inch screen (diagonal) on OnePlus One is excellent for my needs.
* Android is much more customizable and is made for the user. CyanogenMod has made it complete. Add DashClock widgets and it is a near-perfect phone for the user. Not tied to a company who assumes the best for you.